Luminescence immuno-tests are basically well suited for immunoassays as upon careful and competent handling they meet all requirements as to precision and limits of measurement in an optimum manner. However, so far this testing method has remained restricted to a few specialized laboratories, as the handling is relatively complicated and reliable results are obtained only with most careful and competent handling.
A further disadvantage of present luminescence immuno-tests is that the oxidizing reagents initiating luminescence are not storage-stable over long periods of time and, thus, always have to be freshly prepared. This in turn makes the required quality check very difficult and expensive.
Thus, it is a first object of the present invention to bring as many of the necessary reagents and components as possible into a stable form suitable for use in a simplified and reliable quality check.
In Applicant's German Patent Application No. P 34 39 742 there has been proposed a process for initiating light emission by oxidation of phthalic hydrazides in luminescence immuno-tests by the additon of pseudoperoxidase, aqueous sodium hydroxide and aqueous peroxide, wherein the pseudoperoxidase is added to the test batch prior to the measurement and the initiation of the light emission is effected by the addition of an alkaline peroxide solution which is from 0.3 to 10 hours old. Attempts to stabilize the microperoxidase in the dissolved state have failed, as this enzyme has a tendency to decompose, more particularly at elevated temperatures while being shipped or stored, and will lose its activity. Shroeder and Yeager (Analytical Chemistry, Vol. 50, No. 8, pages 1114-1120) investigated various oxidants in a comparative study, resulting in the finding that, hematin and microperoxidase are particulary well suitable as oxidants, subsequently microperoxidase was considered as the catalyst of first choice. However, unfortunately it is still necessary to freshly prepare the microperoxidase solution at least daily and to use it up on the same day. Applicant's investigations lead to the result that hemin and hematin do not give storage-stable solutions, either. Experiments with peroxidase, in comparison to microperoxidase, produced a significantly poorer signal yields, resulting in the finding that peroxidase is less than satisfactory for practical use.